Paper 1 practice questions

Question 1

describe how the body protects against pathogens?

Answer 1

Skin physical barrier
Produces sebum oil which repels pathogens
Tears produce enzymes (lysosome) which repel’s pathogens
cillia and mucus which trap pathogens and move it up the throat to be coughed out
inside the body
Lympochytes create antibodies which kill pathogens
Hydrpochloric acid which kills pathogens

Question 2

In a scientific experiment how could the method be improved for more valid results?

Answer 2

repeat and evalute the mean

Question 3

How is the volume of water lost from the leaves controlled?

Answer 3

Opening and closing of the stomata

Question 4

Describe the transport of water through a plant from the roots to the atomsphere

Answer 4

Absorbed through the roots via osmosis and transported through the xylem
water evaporates and leaves through the opening and closing of the stomata

Question 5

explain why someone with a leaking heart valve would have difficulty while exercising

Answer 5

Valves control the flow of blood - leaky valve means a backflow of blood
Less oxygen is supplied to the muscles
body has to rely more on anaerobic respiration and the lactic acid will cause muscle fatigue

Question 6

Evaluate the use of mechanical replacement heart valves and biological replacement heart valves?

Answer 6

mechanical
Longer lasting
May blood clot of surface of valve
Medication necessary as it could lead to excessive bleeding
Biological
No medication is needed
valve may harden

Question 7

Name a chemical used to test for glucose

Answer 7

Benedicts

Question 8

Name a test that could show a person’s urine contains glucose

Answer 8

Benedicts going from a blue to brick red

Question 9

describe how diabetes can cause body cells to lose more water

Answer 9

Blood is more concentrated (with sugar ), water moves out of cells via osmosis, blood has a low concentration of water so more water will be lost from cells

Question 10

describe how small intestine is adapted for efficient absorption

Answer 10

Large surface to volume ratio
easy access to many blood vessels
Many folds (walls of projection and villi which gives more surface area and short distance to diffuse
walls are only one cell thick
many mitochondria - more energy released

Question 11

define the double circulatory system

Answer 11

Blood to the lungs by the right side of the body
blood to the body on the left side

Question 12

Explain why having only one ventricle makes the circulatory system less efficent

Answer 12

Oxygenated and deoxygenated blood will mix
so less Oxygen will reach the tissues of the body

Question 13

Why would an axolotl die in water with low oxygen concentration

Answer 13

Low oxygen concentration means that gills struggle to diffuse oxygen into the body, Body has to rely on anaerobic which produces toxic lactic acid

Question 14

Name organs in the digestive system that produce carbohydrase

Answer 14

Salivary glands
small intestine

Question 15

explain how pancreatic cancer may cause a person to lose weight

Answer 15

Body cannot create many enzymes , body must use more energy to break down food
less glucose absorped and less avaliable for respiration

Question 16

why are double blind and placebo’s used in clinical trials?

Answer 16

Placebo - to stop the psycholgical effect of feeling better
and double blind to avoid bias

Question 17

Monoclonal antibodies are produced to treat pancreatic cancer , how do they work to treat the cancer?

Answer 17

Monoclonal antiobodies is attached to radioactive substances
Monoclonal will only attach itself to the target cells , the toxin will drug tostop division of cancer cells

Question 18

explain why the mass of eggs that been in water has increased (hint osmosis)

a)

Answer 18

Mass increased because water entered the cell by osmosis
Moved from an area of high to low concentration through a partially permeable membrane

Question 19

Explain how a student could modify an investigation, to determine the solution inside of each egg b)

Answer 19

Changing the solution/solvent of the experiment
use a graph to plot the % change of results

Question 20

explain how calcium ions are moved from the shell to the cytoplasm of the egg

Answer 20

The calcium ions move from an area of low to high concentration by active transport (use ATP energy)

Question 21

An aphid eats by putting it’s mouth into the stem of a plant, the mouthpiece of the aphid now contains high concentrations of dissolved sugars explain why

Answer 21

mouth piece has bitten into the phloem which contains high amounts of dissolved sugars

Question 22

How could a magnesium deficiency cause yellow leaves and stunted growth in a plant

Answer 22

Mg deficiency causes chlorosis which is a lack of chlorophyll -causes yellow leaves
less light is absorbed by the chlorophyll meaning less is used on photosynthesis
Plant makes less glucose so less glucose used to make amino acids = less growth

Question 23

Farmer thinks his crops are infected with PVY virus how would you create the PVY monoclonal antibodies

Answer 23

First isolate the PVY proteins from the virus
inject this proteins into a mouse combine the lymphocytes from the mouse with fast reproducing tumor cells to make the hybridoma cell
this hydridoma cell can make antibodies but can also reproduce quickly like tumor cells
Used to make the antibodies specific to the PVY proteins (specific to the PVY antigen) and can be cloned

Question 24

describe how a student could test cow’s milk to show whether it contains proteins and different types of carbohydrates

Answer 24

for protien
Use biurets solution turns from blue to purple if positive for protien
For carbohydrates
use iodide turns black/blue if positive
For sugars
Use benedicts add a few drops to the milk and boil
the solution will turn from blue to brick red

Question 25

Why is bile rapid at breaking down fats?

Answer 25

the bile emulsifies fats (breaks down fats from large droplets to smaller droplets) creating a larger surface area so lipase is broken down fats to produce fatty acids + glycerol more quickly

Question 26

why is there more antibiotic resistant strains of bacteria?

Answer 26

Due to antibitoics killing non-resistnat strains leading to less competition to multiply

overuse of antibiotics and people not finishing antibiotic course?

Question 27

How does a vaccine make someone immune to a disease?

Answer 27

This is through the vaccine stimulating antibodies
by white blood cells
to rapidly reproduce on re-infection